1. Field of the Invention
The present invention relates generally to a method and system for controlling the use of unauthorized content, and specifically for controlling the display of content that is marked as “copy-never.”
2. Description of Related Art
Various techniques for copy protection of digital information such as music and movies in digital form are known in the art. For example, according to some prior art schemes for copy protection, digital content is marked or flagged to indicate whether and the extent to which the content may be copied. Such flags or marks may include “copy freely,” “copy once,” and “copy never.” As used herein, copy never (or “copy-never”) indicates that further copying of the content is forbidden. Accordingly, when a compliant recording device—one that is looking for content usage right management information—detects the copy-never mark, the compliant recording device will not copy the content. Well-known techniques for marking the content with content usage rights include using the Analog Protection System (APS), Copy Generation Management System for Analog (CGMS-A), Copy Generation Management System for Digital (CGMS-D), and watermarking.
However, such copy protection schemes are subject to certain weaknesses. For example, while compliant recording devices may be prevented from making a copy of copy-never content, there is nothing to prevent an output stream from a media playing device, such as a DVD player, D-VHS player, HD DVD player, computer, or from a broadcast system, from being copied by a non-compliant recording device—one that is not looking for content usage rights management information (such as copy never) and can therefore still copy the content despite the existence of a copy-never mark. Accordingly, illegal copies of copy-never content may be created, which can then be processed or displayed (but not copied) on compliant devices.
It is desirable, therefore, to provide a method and system for controlling the use of illegally copied content by compliant display devices, that overcomes the limitations of the prior art.